In recent years, the semiconductor industry came to realize the necessity for ion implantation equipment in which a high beam current can be obtained even in the lower energy region, so that a shallow junction can be fabricated using boron ions and so forth.
An example is disclosed in Patent Application Publication No. Hei 4-6740. In this ion implantation equipment, a large current of an ion beam is implanted into a substrate through a beam transport system which contains mass analyzer tubes. A deceleration static electrode lens system is provided and consists of three electrodes, having a hole, to provide a large potential gradient and two electrodes, having a hole, for acceleration and deceleration. An ion source is kept at a positive potential at a few kV or higher, but below 20 kV, against the ground potential. The beam transport system between the ion source and the deceleration static electrode lens system is kept at a negative potential at a few or several tens of kV against the ground potential. The first electrode having a hole in the deceleration static lens system is kept at the same negative potential at a few or several tens of kV as the beam transport system. The third electrode having a hole in the deceleration static lens system is kept at the ground potential. The second electrode having a hole in the deceleration static lens system is kept at a middle potential between these of the first and third electrode having a hole. The fourth electrode having a hole in the deceleration static lens system is kept at a negative potential. The fifth electrode having a hole in the deceleration static lens system is kept at the ground potential. The deceleration static lens system is used as a convergent lens as well as for its deceleration function.
In such ion implantation equipment, a high voltage case needs to surround the ion source, an ion extractor system, the mass analyzer tubes, the beam transport system and so forth, so that all components within the high voltage case are insulated from the ground potential. In the above ion implantation equipment, this is achieved by floating the entire high voltage case from the remaining equipment. Hence, the equipment becomes large and manufacturing costs of such equipment becomes expensive. These are the issues.
The purpose of the present invention is to provide ion implantation equipment in which the beam current in a lower energy region can be increased without making such equipment very large and expensive to manufacture.